yay is a development tool designed to enhance workflow efficiency in projects that use a monorepo structure with multiple interdependent packages. It simplifies the challenges associated with concurrently running and managing several yarn start processes for local development of various applications and their dependencies within a monorepo environment.

• Automated process management: yay automatically handles yarn start processes for different packages, allowing developers to concentrate on writing code instead of managing processes.
• Dependency-aware hot reloading: tracks file changes throughout the repository to automatically restart dependent yarn start processes, ensuring updates are propagated across all relevant applications without the need for manual restarts.
• Integrated terminal output: provides a consolidated view of all yarn start process outputs, supporting split-window output for simpler navigation and quicker error analysis.
• File tracking: identifies file changes within the repository, restarting only the necessary processes to conserve time and resources.

git clone [email protected]:lxgreen/yay.git ./yay
cd ./yay
./yay YOUR_MONOREPO_ROOT

yay operates within yarn-based monorepos, utilizing the yarn workspaces command to construct the dependency graph. It assumes each package offers a start script for local development (here, a "yarn process" denotes the yarn start task).

The dependency graph, outlining the locations and dependency/dependent lists for each workspace in JSON format, is queried using the jq CLI tool. This graph is generated once and saved at the monorepo's root as dep-graph.json. To ensure accuracy, this graph must be deleted and regenerated whenever the monorepo's structure changes.

Upon initialization with a monorepo root path, yay prompts the user to select an application for development and its necessary transitive dependencies for monitoring. It's vital to choose only essential dependencies due to the resource intensity of each yarn process. The selected application's dev server starts immediately, with all chosen dependencies monitored for source changes. The entr CLI tool is used to track file changes, triggering the respective dependency's yarn start upon any source modification.

Outputs from each yarn process are monitored, a necessity due to yarn lacking an API for task progress tracking. The monitoring detects a build's completion message (e.g., 'Compiled successfully'), triggering a callback. This callback updates the tracking log files (located at /src/.track_me within each workspace) of dependent packages. Updating these tracking logs serves two functions:

1. It triggers a restart of any running dependent package yarn start processes (interpreted as a source code change by yarn).
2. It marks the dependent package as 'dirty' for other yarn processes reliant on that package's source.

Potential Improvement: Consider exploring alternative IPC mechanisms for enhanced reliability.

tmux is used to organize the output of multiple processes, with each yarn process running in its dedicated tmux pane. yay starts a separate tmux server with a custom configuration to avoid possible interference with the local environment.

The session is divided into two windows:

1. The build window, which displays the yarn process panes.
2. The trackers window, which is hidden by default and shows the panes for source change tracking commands. When a tracker initiates a new yarn process, it is displayed in a new pane within the build window.

• node
• yarn
• fzf
• jq
• entr
• timeout
• tmux